The invention generally relates structures for supporting one or more diagnostic or therapeutic elements in contact with body tissue. In a more particular sense, the invention relates to structures well suited for supporting one or more electrode elements within the heart.
The treatment of cardiac arrhythmias requires electrodes capable of creating tissue lesions having a diversity of different geometries and characteristics, depending upon the particular physiology of the arrhythmia to be treated.
For example, it is believed the treatment of atrial fibrillation and flutter requires the formation of continuous lesions of different lengths and curvilinear shapes in heart tissue. These lesion patterns require the deployment within the heart of flexible ablating elements having multiple ablating regions. The formation of these lesions by ablation can provide the same therapeutic benefits that the complex incision patterns that the surgical maze procedure presently provides, but without invasive, open heart surgery.
By way of another example, small and shallow lesions are desired in the sinus node for sinus node modifications, or along the A-V groove for vanous accessory pathway ablations, or along the slow zone of the tricuspid isthmus for atrial flutter (AFL) or AV node slow pathways ablations. However, the elimination of ventricular tachycardia (VT) substrates is thought to require significantly larger and deeper lesions.
There also remains the need to create lesions having relatively large surface areas with shallow depths.
The task is made more difficult because heart chambers vary in size from individual to individual. They also vary according to the condition of the patient. One common effect of heart disease is the enlargement of the heart chambers. For example, in a heart experiencing atrial fibrillation, the size of the atrium can be up to three times that of a normal atrium.
A need exists for electrode support structures that can create lesions of different geometries and characteristics, and which can readily adopt to different contours and geometries within a body region, e.g., the heart.
The invention provides structures for supporting operative therapeutic or diagnostic elements within an interior body region, like the heart. The structures possess the requisite flexibility and maneuverability permitting safe and easy introduction into the body region. Once deployed in the body region, the structures possess the capability to conform to different tissue contours and geometries to provide intimate contact between the operative elements and tissue.
The invention provides a catheter assembly comprising a sheath, which includes a side wall enclosing an interior bore, a distal region, and an opening in the sidewall. The assembly also includes a bendable catheter tube, which is carried for sliding movement in the interior bore. The catheter tube has a distal portion. The assembly further comprises a coupling, which joins the distal region of the sheath and the distal portion of the catheter tube. The coupling causes bending of the catheter tube outwardly through the opening, in response to sliding movement of the catheter tube within the interior bore toward the distal region of the sheath.
In one embodiment, bending of the catheter tube forms a loop, which extends outwardly of the opening and which is supported near the sheath by the coupling. In this embodiment, the coupling comprises a flexible joint.
In one embodiment, the catheter tube carries at least one operative element, e.g., an electrode.
Other features and advantages of the inventions are set forth in the following Description and Drawings, as well as in the appended Claims.